Tensiometer



May 26, 1942- r".v BJBREAZEALE 2,284,364

l TENSIOMETER y Filed March '7, 1940 2 Sheets-Sheet l May 26, 1942- B. BREAzl-:ALE 42,284,364

TENsioMETER Filed March 7, 1940 2 Sheets-Sh'eet 2 me/MM Patented Meyfze, 1942 Francis B. Breazeale, Enka, N. C., `assignor to American Enka Corporation, Enka, N. C., a corporation o! Delaware A Application March 7, i940, Serial No. 322,824

d 2 Claims. (Cl. 265-L6) This invention relates to the measurement of thread tension and particularly to an improved apparatus that is capable of measuring the ten-- sion of threadand recording this'me'asurement ,while the thread is passing the measuring de-V vice at a very rapid rate'.

Particularly in industries such as the artificial silk industry lin which enormous quantities of filaments or threads are continuously produced and very rapidly-handled, it isuhighly desirable,

- as a matter of quality control, to be able to measure such physical constants as the tension to which thread. is subjected at various stages of the operation with sufilcient rapidity so that the measuringcauses no .delay in the process.

Various mechanical devices for measuring thread of iixed rollers II and I2 and over a movable tension have been proposed but these devices almost invariably lack sensitivity and contain so many moving parts and parts of such weight vthat their inertia causes'them to completely miss many sudden variations in ltension and to follow onlyv general variations over prolonged periods of time which detect neither flaws in the thread nor certain types of improper functioning of the machinery.

The present inventionhas for its object the provisionof a thread tension recorder that will f operate accurately and at sumciently high speeds so that it will detect flaws in the thread and even the vmost minor of misfunctionings of the machinery. For this `purpose the present invention provides a simple eicient device .in which the tension of the thread is applied against the torque in a wire held under -torsin Aand the balance between these two forcs is indicated by the position'y of a very light weight slider on a resistance. The position of this slideron a resistance governs the operations of an oscillograph recorder of any desired type, as f or exampleJfa combination of cathodevray oscillograph and 'av camera or a recording vgah/anom-` eter.

illustrate the preferred embodiment of this invention and a study of these drawings and the `fo1lowing description of them will yield a better understanding of the principles-and details and advantages of Vthis invention. However, it is to be understood that the invention is not limited to the preferred embodiments shown, and

The drawings i appended to this application' presentinventicn and applied ina relatively simple form. Figure 2 is a perspective view of the measuring instrument itself. Figure 3 isa 'diagrammatic illustrationof the device as it may be -used employing a cathode ray tube and' a "camera Vfor recording the.results. Figure 4 is a diagrammatic illustration of thejpresent invenl tion showing use of a variable capacitance in the electrical circuit andl Figure 5 isa similar illustration wherein the variable capacitance is replaced by a variable inductance.

As illustrated in Figure 1 the be measured `for tension passes around a pair roller I3 carried on a light weight lever I4 fixed to and carried by a torsion wire I5. The torsion wire I5 itselfv is carriedin. fixed blocks I6 and Il, the block I6 being near the end of the torsion wire that carries the lever I4 and the torsion wire being rotatable in this block. The block II, on the other hand, is further removed from the lever I4 and the` wire I5 is fixed to this block by a set -screw I8 so that it cannot turn. Thus when tension is -applied to the thread .I it exerts a force on the pulley i3 which tends vto revolve the lever I4 and.v twist the wire I between the lever I'4 and the block l1 in which it is xed against rotation. r'.By reason of the low moments'of inertia of the moving parts the device quickly reaches the point of equilibrium where the rotating force exerted by the thread on the wire I5 vexactly balances the force be driven at a constant rate or may be-drivenv that-the principles of thisinvention may be applied in v'any way and with anyn'iodication consistent with the claims of this application.

In the drawings:

Figure I is a diagrammatic illustrationof the exerted by the wire in attempting to restore itself to its normal position. s

In order to record the'position of'theflever |41 t when this positionof equilibrium is reached, a

light weight slider or contactar I9 .is aixed to ythe lever I4 and arranged to move along aresistance L ,A battery 2 I or similar source of potential may be applied across the resistor 2|!l and an amplifier may have its input connected by connections` 22 and 23 to the slider I 9 and .one terminal of the battery ZI so that the voltage ,to the input. of the 'amplifier 24 will-be varied as the positionof'the lever I4 'isvaried. From'A the lamplier 24v the current passes through leads 25 to a recording galvanometer 26, where the measurements are recorded onv a record strip or tape 21. y f j The recording tape of the galvanometer may through a gearing arrangement from the same power source ,that drives the thread Ill. `For this purpose a shaft I2a is provided, connected to the roller I2 and adapted to drive the record strip of the recording galvanometer 21 through the gearbox I2b substantially as illustrated. In

this latter case a close correlation can be made between the tension recorded and'the particular length'of thread that was passing under the 5 tensioning device when the recording was made. The specic device that applicant has con- 'structed and found highly desirable as a tension measuring device is illustrated in greater detail in Figure 2 of the drawings. It comprises es- 10 sentially .the same elements as have been described in connection with Figure 1. LIn this device the xed pulleys II and I2 are mounted in brackets 28 which inturnare carried by a main frame 29. `From an upstanding-ear 30 on 15 the main frame 29. there extends a x'ed'hori.

zontal bar 3| on which the torsion wire `holding of set screws 32 and 33. Smaller set screws -34 i `hold the torsion wire I in the block I1 which 20 is remote from the light torsion lever I4 and' the wire I5'is rotatably heldin the block I6 by passing it through a small opening in this block. The movable pulley I3 is mounted on the end of the torsion bar I4 as before and the torsion 25 lever I4 is xed tothe end of the torsion wire I5 and extends on past the torsion wire and against. the resistance which is held to a non-conducting arm by means of clamps 36 and 31. The non-conducting arm 35 is bolted .30 on to the base plate 29 by screws 33. Each of the resistance holding clamps 36 and 31 carries l clamping screw 39 which can be manually released so that' the clamps '3 6 and 31 can be moved closer together or further apart to adjust 35 thesensitivity and range of the testing device.-

The clamps 36 and 31 are connected to the opposite ends of a source oi' potential, not shown l in Figure 2 but shown as battery 2| in Figure 'l l, by'ineans ofl conductors 40 and 4|. The piv- 40 oted lever I4 and hence the slider I3 is connected through the torsion wire at the blocks I8. and I1 back to the frame and the connection 42 conveys this potential to the amplifier 24 or whatever recording equipment is used.

In Figure 3 is diagrammatically illustrated the particular recording arrangement that has been actually used by the applicant and in this arrangement the tension measuring part of the device is the same as that shown in Figure 2. 50 The device differs. however, in that theleads 22 and 23 instead of being carried to a separate ampliiler are connected directly to a cathode ray oscillograph 43 so that the measurements being made are constantly visible on the window 55 oi'- the cathode ray tube 44. In order to recordv 'these measurements a movingpicture camera 45 is provided and focused on the cathode ray tube I 44. This motion picture camera is driven by motor 46 which in turn is supplied with power 60 the camera may be omitted so that a continuous trace of the action of' the cathode ray tube is 70 made rather than a series of separate pictures.

In Figure 4 a'recording arrangement is illustrai'ed similar to that shown in Figure l with ,the exception that the variable resistor 23 is replaced Vin the electrical circuit by the com- 76 bination of a ilxed inductance 50 and a variable capacitance 5I. is relatively movable and is mechanically coupled to the lever I4 whereby movement of the lever is reilected in change of value of the capacitor. The inductance 50 is connected in parallel circuit with the capacitor and the combination is connected in series circuit with the pcof the lever I4 as above mentioned. The other elements of the device function in the same manner as the correspondingly numbered elements of Figure 1. An advantage of replacing the variable resistor with a variable capacitance in the vdevice according to this invention is that frictional energy losses due to rubbing of the slider I9 againsththe body of the resistor 20 vare eliminated thereby increasing the sensitivity and accuracy of the instrument.

In Figure 5 another modiilcation of the basic arrangement toFigure 1 is illustrated wherein the variable resistor 20 is replaced with the combination lof a variable inductance 52 and a'. xed capacitor 53. The combination, the elener similar to that described in connection with Figure 1. An advantage arising from replacing the variable resistor with a variable inductance.

as in the use of a variable'capacitor, is the elimination of the frictional losses due to 'rubbing of the slider against the resistor. In a device that has actually been used all of thewheels are of aluminum and mounted on jewel bearings. The tension on the wire I5 may be adjusted by loosening the screw. I3 land thel 'sensitivity and range of the device may be ad' been found possible to make tlietotal weight of the 'pivoted lever as low as about 1 grams and the frictional resistance of the slider against the resistor' aslow.as around 0.1 to 0.2 gram.

By adjusting the length of the torsion wire employed and the torsion placed upon it the period of natural vibration oi.' the lever arm can be adjusted so as 'not' to interfere with accurate recording. I

Numerous modifications will immediately be apparent to those skilled in the art and it is not intendedthat the description of the preferred embodiment be construed as limiting the posslble'applications of this invention.'

.Iclaimz T 1. A device for measuring the tension of moving threads, lament'sor the likethatcomprises a substantially straight, rod-like, torsion element. means for anchoring the torsion element at one point in itslength, means for directly supporting said element, ireefor rotation. at another point-in its length. a. lever arm attached I to and extending laterally from said torsion ele- Y ment at a poin't .removed from the anchoring One plate of the capacitor 5Iv rectly supporting said element, free for rotation,

means, means supported by andvdirectly mounted on said lever arm for guidinga moving thread, filament orr-the-like, means inthe same plane as the first mentioned guiding means for guiding a moving thread, lament or the like over said rst mentioned guiding -means in- 'such a manner that the tension of the thread, `lament or the like-will tend to rotate the supportingflever arm at another point in its length, a lever arm attached to and extending laterally from 'said torsion element at a point removed from the anchoring means, means supported by anddirectly mounted on said lever arm for guiding a Y moving thread, filament or the like, means in' the same planel as the rst mentioned guiding means for guiding a moving thread, iament or the like over'said iirst mentioned guiding means in such a manner that the tension' ofA the "thread, mamen; or the like will tend to rotate the supporting lever arm about the axis of the torsion element, and electrical means to determine the extent of :rotation caused thereby.

' FRANCISAB, BREAZEALE. 

